diff -r b1b57391bc4e -r ed45a5fb4452 hgext3rd/topic/__init__.py
--- a/hgext3rd/topic/__init__.py	Fri Jul 07 01:01:01 2017 +0200
+++ b/hgext3rd/topic/__init__.py	Thu Jul 06 03:56:36 2017 +0530
@@ -294,7 +294,24 @@
         ('l', 'list', False, 'show the stack of changeset in the topic'),
     ] + commands.formatteropts)
 def topics(ui, repo, topic='', clear=False, rev=None, list=False, **opts):
-    """View current topic, set current topic, or see all topics.
+    """View current topic, set current topic, change topic for a set of revisions, or see all topics.
+
+    Clear topic on existing topiced revisions:
+        `hg topic --rev <related revset> --clear`
+
+    Change topic on some revisions:
+        `hg topic <newtopicname> --rev <related revset>`
+
+    Clear current topic:
+        `hg topic --clear`
+
+    Set current topic:
+        `hg topic <topicname>`
+
+    List of topics:
+        `hg topics`
+
+    The active topic (if any) will be prepended with a "*".
 
     The --verbose version of this command display various information on the state of each topic."""
     if list: